The effect of vaccination on the biochemical inflammatory markers and disease severity during the third wave of COVID-19 in Tamil Nadu

Corona Virus Infectious Disease-19 (COVID-19) is a pandemic that started in December 2019 and continues to infect people worldwide. The vaccination program against COVID-19 began in India in January 2021 and has completed 2.2 billion doses as of 4th March 2023. The clinical presentation of COVID-19 patients during the third wave was found to be mild, and the need for hospital admission and oxygen support was greatly reduced during the third wave, which may be attributed to the vaccination program or the variant per se (Omicron). The serum levels of the inflammatory markers like interleukin-6, ferritin, D-dimer, lactate dehydrogenase (LDH), and albumin of the patients admitted to our hospital from December 2021 to February 2022 were collected. The levels of these inflammatory markers were compared with the patient’s vaccination status and disease severity. Ferritin and D-dimer were significantly higher in non-vaccinated patients compared to patients who were vaccinated. The severity of the disease was significantly higher in the non-vaccinated patients (21.4%) than in the single-dose (4.3%) and two-dose (16.7%) vaccinated patients, with a Pearson chi-square value of 11.59 (p = 0.02). IL-6, ferritin, D-dimer, and LDH exhibited a significant positive correlation (p < 0.001) among them, whereas serum albumin exhibited a significant negative correlation (p < 0.001) with IL-6, ferritin, D-dimer, and LDH. The vaccinated patients had significantly reduced levels of inflammatory markers than the non-vaccinated patients, which shows that vaccination has significantly decreased the severity of COVID-19.